Anti-greying agents have the task of keeping the dirt, that is detached from the fiber during the washing of textiles, suspended in the liquor, thus preventing the dirt from being redeposited on the textile. Water-soluble colloids, usually of organic nature, are suitable for this purpose, for example glue, gelatin, or salts of acidic sulfuric acid esters of cellulose or of starch. Water-soluble polyamides containing acidic groups are also suitable for this purpose. Furthermore, soluble starch preparations and starch products other than those mentioned above can be used, for example degraded starch, aldehyde starches, etc. Polyvinylpyrrolidone can also be used. Cellulose ethers such as carboxymethyl cellulose (Na salt), methyl cellulose, hydroxyalkyl cellulose, and mixed ethers such as methyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose, methyl carboxymethyl cellulose and the mixtures thereof in quantities of normally 0.1 to 5% by weight, in relation to the detergent, are often also used.
Although the specified cellulose ethers have a good anti-greying effect, the use thereof in hydrous liquid detergents is highly restricted, such that they cannot be incorporated in such detergents in practice. Apart from their anti-greying effect, which only becomes relevant with use in the washing process, these cellulose ethers specifically have a comparatively low solubility in surfactant-containing systems and have a highly thickening effect on aqueous systems. When such cellulose ethers are incorporated, in concentrations desired for the anti-greying effect, into liquid detergents containing water and in particular containing anionic surfactant, either products that are no longer flowable and pourable are generally obtained, which products can only be handled by the user with additional effort, for example by providing individual metered portions packaged so as to be water-soluble or so as to be capable of being torn open and water-insoluble, or the cellulose ethers are, in particular after storage, not fully dissolved in the hydrous liquid detergent or are not uniformly dispersed therein, which, besides a poorly perceived aesthetic appearance, also leads to non-uniform metering of the anti-greying active ingredient in the case of application of the agent containing same.
International patent application WO 2006/117056 A1 discloses the use of celluloses that carry sulfoalkyl groups bonded via ether, ester or amide functions for prevention of redeposition in the washing of textiles.
It has now surprisingly been found that a good anti-greying effect without unacceptable viscosity increase or precipitation can be achieved in hydrous liquid detergents when sulfoethyl cellulose is used.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.